llamindex for TypeScript is in its early stages compared to the Python version. Still, it already offers great flexibility if you don't want to change the language of your Proof of Concept or your project (honestly, I haven't made anything production-ready yet, so DYR).

You will need to use the package @llamaindex/community because natively, we can't use Bedrock in the llamindex core package, so for this purpose, install @llamaindex/community, it is a package managed by the llamaindex team.
Basically, it's a secondary distribution as it seems to be a way to externalise the open-source contribution (dunno why, but ok)

Cut to the chase

import { BEDROCK_MODELS, Bedrock } from '@llamaindex/community'
 Settings.llm = new Bedrock({
    model: BEDROCK_MODELS.ANTHROPIC_CLAUDE_3_HAIKU,
 })

I discovered this handy tip while reviewing a pull request's readme. It took some effort to figure it out, so I hope it's helpful to you.